使用 java 包去連線 s3 並且向 s3 上傳檔案，需要有 s3 的包，此處我用的是 maven 專案去匯入 s3 的包，在 pom.xml 中加入如下內容

    <dependency>
        <groupId>com.amazonaws</groupId>
        <artifactId>aws-java-sdk-s3</artifactId>
        <version>1.11.347</version>
    </dependency>

此時 maven 會自動匯入相關的依賴包：

最後是程式碼部分：

import java.io.File;
import java.io.IOException;
import java.net.URL;
import com.amazonaws.AmazonClientException;
import com.amazonaws.AmazonServiceException;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.regions.Region;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3Client;
import com.amazonaws.services.s3.model.CannedAccessControlList;
import com.amazonaws.services.s3.model.GeneratePresignedUrlRequest;
import com.amazonaws.services.s3.model.PutObjectRequest;
import com.amazonaws.services.s3.transfer.TransferManager;

public class UploadTest {

    AmazonS3 s3;
    String AWS_ACCESS_KEY = "xxxxxxxx"; // 【你的 access_key】
    String AWS_SECRET_KEY = "xxxxxxxx"; // 【你的 aws_secret_key】

    String bucketName = "xxxxxxx"; // 【你 bucket 的名字】 # 首先需要保證 s3 上已經存在該儲存桶

    static {
        s3 = new AmazonS3Client(new BasicAWSCredentials(AWS_ACCESS_KEY, AWS_SECRET_KEY));
        s3.setRegion(Region.getRegion(Regions.US_EAST_1)); // 此處根據自己的 s3 地區位置改變
    }

    public String uploadToS3(File tempFile, String remoteFileName) throws IOException {
        try {
            String bucketPath = bucketName + "/upload" ;
            s3.putObject(new PutObjectRequest(bucketPath, remoteFileName, tempFile)
                    .withCannedAcl(CannedAccessControlList.PublicRead));
            GeneratePresignedUrlRequest urlRequest = new GeneratePresignedUrlRequest(bucketName, remoteFileName);
            URL url = s3.generatePresignedUrl(urlRequest);
            return url.toString();
        } catch (AmazonServiceException ase) {
            ase.printStackTrace();
        } catch (AmazonClientException ace) {
            ace.printStackTrace();
        }
        return null;
    }

    @Test
    public void test(){
        File uploadFile = new File("c:/test.txt");
        String uploadKey = "test"
        uploadToS3(uploadFile,uploadKey);
    }
}